1 Field of the invention
This invention relates to a security device, and, in particular to a security device for emergency door latches equipped with a depressable crash bar. 2. Brief statement of the prior art
Emergency and exit doors of public doors of public buildings and the like are required to have latch mechanisms that can be safely operated by occupants of the building. Typically these doors have a latch mechanism bearing a crash bar that is pivotally mounted by distal pivot arms to extend transversely across the inner face of the door. This latch mechanism presents substantial security problems since the crash bar can be actuated from the exterior of the door by inserting a wire hook through the crack between the doors of a pair of double swinging doors or the crack between the door and the door jam of single doors. An effective and automatic locking mechanism has not been designed for these doors, particularly because of the safety requirement that such lock mechanisms not defeat or interfere with the free opening of the door by actuation of the crash bar. One lock mechanism, disclosed in U.S. Pat. No. 212,957, employs an arm carried on the inner face of the door and bearing a clasp that can be fastened about the crash bar. One difficulty with this device is that it cannot be used under most municipal safety codes whenever the building is occupied because it restrains the crash bar against free movement. Another locking mechanism, disclosed in U.S. Pat. No. 3,877,262, is useful with a crash bar that is mounted for translation rather than pivotal movement.